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On Monday 31 August 2015 11:42:28 Alan McKinnon wrote: |
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> On 31/08/2015 10:50, Peter Humphrey wrote: |
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> > The desktop machine I'm referring to (an Amari "workstation") dates from |
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> > 2009. It has an i5 processor, 16GB RAM* and two 2GB SSDs as the main |
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> > power sinks. It sits (runs) in a boxroom 6ft square and keeps it |
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> > comfortably warm. I haven't noticed any change in ambient temp since the |
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> > SSDs replaced spinners. |
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> > |
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> > * Whoever named that Random Access had a strange understanding of English. |
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> > The last thing I want from memory is random access! How much better it |
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> > would have been to call it something like Direct Access. Oh well - much |
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> > too late now. |
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> |
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> It's random access to distinguish it from serial access. In the early |
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> early days there were a lot of strange methods being tried to build |
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> memory - like dots on a cathode ray tube! To get to bit you wanted, you |
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> had to wait till the scanning beam reached that part of the screen - |
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> serial access. Addressable memory on a grid pattern came much later. |
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Yes, of course I know all that, but it's still the antithesis of random - it's |
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absolutely specific. Random is what you'd get if you didn't specify anything. |
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My favourite storage medium was core store. Millions of tiny ferrite rings, |
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each at an intersection of orthogonal X and Y wires to specify the address, |
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and a write pulse on another wire on the Z axis. At least, that's as close as |
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I can remember now, 40 years later. No wonder computers were expensive. |
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I won't tell you what systems used a 24-bit processor and 12 or 16 KB of 2us |
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core store backed by a 2MB disk (three feet in diameter), for fear of |
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frightening you. ;-) |
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> Random Access really means "able to access any random address as fast as |
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> any other random address". |
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My point is simply that the addresses are very far from randomly chosen. The |
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distinguishing feature of the store is that you can go directly to the |
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required location, without having to wait for it to reach the read/write |
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device. |
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As I said though, there'd be no point in getting all stressed about it now. |
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> RAM is also not the opposite of ROM :-) |
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I seem to be having a senior moment here; at least, I don't follow that. |
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-- |
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Rgds |
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Peter |
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